Effect of axial magnetic field on TIG welding–brazing of AA6061 aluminum alloy to HSLA350 steel

External magnetic field (EMF) is favored for application in welding, due to its positive effects on joint quality. In the present study, the effect of EMF on AA6061 Al alloy/HSLA350 steel welded joints were investigated. When no EMF, coarse Al grains were formed on the welded joint. The second phase including Al–Si eutectic and large Al3FeSi slats exists in the joint fusion zone. Refinement of the Al matrix and second phases were produced as a result of the Lorentz force generated by the 380 mt EMF treatment. The joint strength with EMF treatment at welding current 60 A increased from 170 MPa (without EMF treatment) to 195 MPa and the joint ductile fracture position was on the Al alloy base material under this same condition, due to the fine grained strengthening and dispersal strengthening of the second phases, meanwhile, the intermetallic compounds (IMCs) layer at the Al/steel welding seam interface was significantly reduced.